The present invention relates to devices for converting radiant energy into electricity and electricity into radiant energy, and methods of making them. More specifically, the present invention relates to such devices which contain a compound of aluminum with one or more elements from Group V of the periodic table. The invention also involves a method for preventing deterioration of such aluminum-V compounds.
Direct conversion of light into electrical energy by solar cells is important in outer space applications. New and better earthbound sources of electrical energy are in great demand as well. Long operating life, high efficiency at high temperatures, and low cost are important device goals in both environments.
Aluminum-V compounds such as aluminum arsenide have begun to be investigated for possible use in photovoltaic devices, including solar cells. These compounds have been expected to exhibit a high bandgap and provide a good lattice match with III-V compounds such as gallium arsenide, although operative heterojunctions of such a type, grown by vapor phase epitaxy, have not heretofore been demonstrated. Unfortunately, aluminum-V compounds are also known to react with water and water vapor, and deteriorate when left in the open air. These problems have been thought to limit the potential usefulness of such compounds in device applications. Now, however, these problems can be solved according to an invention herein disclosed.